Why does my Magic Trackpad lock up a short while after wakening from computer sleep? I have OSX Mavericks on my iMac.

I have a 2009 iMac dual core intel with OSX Mavericks. I added a magic trackpad and I find that it occasionally locks, particularly a short while after the computer is awakened from sleep. The connection is not lost and I have to use another mouse to disconnect and then reconnect to bluetooth. Alternatively, I remove the batteries and reinsert, then press the connect buton.